[Objectives, tools and methods for an epidemiological use of electronic health archives in various areas of Italy]. / Obiettivi, strumenti e metodi per un utilizzo epidemiologico di archivi sanitari elettronici correnti in diverse aree italiane.

The availability of Electronic Health Archives (EHA) has increased remarkably over the last twenty years. As part of a joint project of the Italian Association of Epidemiology (AIE) and the Italian Association of Medical Statistics and Clinical Epidemiology (SISMEC), a workgroup of experts was set up in 2005 with the aim of comparing various experiences and of standardizing the procedures by which electronic sources can be integrated. In particular, the workgroup's aim was to estimate the frequency of certain major diseases using standard algorithms applied to EHA. This volume is published with the purpose of making available in a common publication the methods and the results obtained. The results from a multicentre study using a standard approach to probabilistic record-linkage procedures are also included in a specific chapter. Eleven Italian centres from five Italian regions with an overall population of 11,932,026 collected and treated more than 21,374,426 records (year 2003) from five electronic information sources: death certificates, hospital discharge records (including outpatient discharges), drug prescriptions, tax- exemptions, and pathology records in order to estimate the frequency of the following diseases: diabetes, ischemic heart diseases, acute myocardial infarction, stroke, asthma, chronic obstructive pulmonary disease, obstructive lung diseases. For each pathology a specific algorithm was developed and used by all centres for the identification of the prevalent/incident cases of the selected diseases. Standardized methods were used to estimate the rates. The results confirm the need for a common standard approach to produce estimates based on EHA, considering the variability of the quality and of the completeness of the archives, and the difficulties of standardizing record-linkage operations in the various centres. The main achievement of this work was the elimination of the variability due to the use of different algorithms to identify cases using EHA.

[Acute myocardial infarction incidence estimated using a standard algorithm based on electronic health data in different areas of Italy]. / Stima dell'incidenza dell'infarto miocardico acuto basata su dati sanitari correnti mediante un algoritmo comune in differenti aree italiane.

AIM: to define and implement an algorithm, based on current databases, in order to estimate acute myocardial infarction (AMI) incidence in six Italian areas. SETTING: Local Health Units of Firenze and Venezia, and the municipalities of Pisa, Roma, Taranto, and Torino. PARTICIPANTS: residents in the above mentioned six areas in the period 2002-2004, for a total of about 4,447,000 subjects (30th June 2003). METHODS: acute myocardial infarction incident cases were identified through hospitalization databases and causes of death. Hospital discharges (excluding outpatient discharges) with ICD9-CM code 410* as primary discharge diagnosis, or as secondary diagnosis when associated with selected codes suggestive of ischemic symptoms in primary diagnosis, and deaths with the ICD9-CM code 410* as underlying cause were selected. Patients without a previous hospitalization for ICD9-CM codes 410* and 412* during the previous 60 months were considered as incident cases. Crude, age-specific and age-standardized incidence rates (standard: total Italian population at the 2001 census) were calculated. A number of data quality indicators were also evaluated. RESULTS: age-standardized incidence rates show different levels of incidence in the areas included in the study. Both for males and females, higher incidence is observed in Rome and Turin (males: respectively 260.5 and 260.2 cases/100,000; females: 105.6 cases/100,000 in both areas). The lowest incidence is observed in Taranto (males: 219.5 cases/100,000; females: 87.0 cases/100,000). Quality indicators suggest a good comparability of incidence estimates among the studied areas. In particular, in both genders, the differences observed in the incidence rates are consistent with the differences of current AMI mortality rates. CONCLUSIONS: although limitations in data comparability among the studied areas and in the quality of disease coding cannot be completely excluded, results suggest that the algorithm we used provides estimates of AMI incidence rates comparable among the studied areas. Only a validation study with standardized criteria will make it possible to more closely evaluate the diagnostic quality and comparability of AMI cases identified through this algorithm.

[Ischemic heart disease prevalence estimated using a standard algorithm based on electronic health data in various areas of Italy]. / Stima della prevalenza della cardiopatia ischemica basata su dati sanitari correnti mediante un algoritmo comune in differenti aree italiane.

AIM: to define an algorithm to estimate prevalence of ischemic heart disease from health administrative datasets. SETTING: four Italian areas: Venezia, Treviso, Torino, Firenze. PARTICIPANTS: resident population in the four areas in the period 2002-2004 (only 2003 for Firenze) for a total of 2,350,000 inhabitants in 2003. MAIN OUTCOMES: annual crude and standardized prevalence rate (x100 inhabitants), 95% confidence intervals by area. Quality (comparability and coherence) indicators are also reported METHODS: the algorithm is based on record linkage of hospital discharges (SDO), pharmacological prescriptions (PF), exemptions from health-tax exemptions (ET) and causes of mortality (CM). From SDO we extracted discharges for ICD9-CM codes 410*-414* in all diagnoses in the estimation year and during the four years immediately preceding. We selected from PF subjects with at least two prescriptions of organic nitrates (ATC = C01DA*) in the estimation year. From ET subjects with a new exemption for ischemic heart disease (002.414) or who obtained exemption in the three years preceding, were selected. We also considered all deaths in the year for ischemic heart disease (ICD9 CM 410-414). Cases were defined as ischemic heart disease prevalent cases if they were extracted at least once from one of the datasets and if they were alive on January 1 of the estimation year. RESULTS: estimated crude prevalence ranges from 2.5 to 4%. The standardized prevalence led to a narrower range of values (2.8-3.3%). Venezia and Firenze show a higher standardized prevalence in both sexes (men 4.7% and 4.4%; women 2.3% and 2.2% respectively); Treviso and Torino present a lower standardized prevalence (men: 3.9%; women: 1.9%). The hospital discharges are the main source to identify prevalent subjects (34-48% of subjects are solely identified by SDO), pharmacological prescriptions are a relevant source in Firenze and Torino (27-28%), while they are less relevant in Venezia and Treviso (13-15%). ET shows a different contribution to prevalent case identification in the four areas: Venezia (8%), Treviso (3.2%), Firenze (1.3%), whereas in Torino this source was not available at all. Subjects classified as prevalent cases only through causes of death are less than 2%. The percentage of subjects simultaneously identified by multiple sources is high in Venezia (43%) and low in Torino (30%). CONCLUSIONS: patterns in use of pharmaceuticals and exemptions from prescription charges appear to be heterogeneous in the different areas under study. These two aspects make a proper comparison between areas difficult. The algorithm could be applied only in areas with a similar use of organic nitrates and with a good comparability of the exemptions dataset.